Genoise 

1. Preheat oven to 329°F / 165°C and line the bottom of a 8 inches / 20 cm round cake pan with parchment paper.
2. In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs and sugar at medium-high speed for 10 - 12 minutes until the mixture triples in volume.
3. Stop the mixer and pour the cake flour through a fine sieve and gently fold in with an angled spatula until the mixture is smooth and homogeneous (without making the batter fall apart).
4. Pour the genoise batter into the prepared cake pan and bake for 20 minutes until golden on top (check for baking by plunging a toothpick into the center, it should come out clean without crumbs).
5. Let the sponge cool a bit in its pan before unmolding it carefully by running a knife around the edge of the pan, then let it cool completely on a cake rack.
6. Cut the sponge cake into 2 layers of about 1 cm thick with a cake leveler or a large serrated knife.
7. Cover with a cloth and keep at room temperature for the rest of the preparation.
   
   

Diplomat cream filling

1. Rehydrate the gelatin leaves in a bowl of cold water for 10 minutes.
2. Bring the milk and vanilla bean to a boil, previously split in two and scraped to remove the seeds, then leave to infuse for 10 minutes if possible.
3. Meanwhile, whisk the egg yolks with the sugar and cornstarch in a large bowl until the mixture is whitened.
4. Pour the hot milk through a sieve over the yolk mixture and whisk until smooth.
5. Transfer the mixture to the saucepan and bring to a boil over medium heat until the pastry cream thickens, stirring constantly with a hand whisk.
6. As soon as it starts to boil, continue to cook the pastry cream for another 2 minutes.
7. Remove from the heat and add the gelatin sheets first and mix vigorously to incorporate them, then add the softened butter and mix again.
8. Pour the pastry cream into a rectangular dish and cover with plastic wrap.
9. Place the pastry cream in the refrigerator until it is completely chilled.
10. When the pastry cream is cold, put it in the bowl of a stand mixer with the whisk attachment and mix on medium-high speed for 1-2 minutes to relax it.
11. In a separate bowl, whip the cold heavy cream with the cold mascarpone cheese with an electric mixer at medium speed for 3 minutes until you have a firm whipped cream.
12. Add the whipped cream to the pastry cream with a spatula until you have a smooth, unctuous diplomat cream.
13. Cover and store in the fridge until ready to assemble.

Set up 

1. Place a pastry ring on a cake board or in a large serving dish.
2. Place halved strawberries around the edge of the circle, making sure not to leave any space between the strawberries.
3. Place first re-cut sponge cake about 6 inches/ 16 cm in diameter (use a plate or tart circle to cut out the bottom layer of genoise).
4. Apply the soaking syrup with a pastry brush over the entire surface of the genoise.
5. Then cover the entire genoise and fresh strawberries with the diplomat cream until completely covered.
6. In the center, add some strawberry chunks and cover again with a layer of diplomat cream.
7. Place the second genoise of 8 inches / 20 cm in diameter and soak it with sugar syrup.
8. Cover completely with the filling and smooth with an angled spatula.
9. Place the strawberry cake in the refrigerator for about 1 hour before unmolding.

Decoration 

1. Whip the remaining diplomat cream filling with an electric whisk to give it a fluffy texture.
2. Decorate the top with a piping bag and the filling, then decorate the center with fresh strawberry slices.
3. Enjoy the cake.